In the past, imaging elements such as CCD (Charge Coupled Device) and CMOS (Complementary Metal Oxide Semiconductor) image sensors have been used in electronic equipment having an imaging function such as digital still camera and digital video camera.
An imaging element has pixels that include PDs (photodiodes) that convert light into an electric current and a plurality of transistors, creating an image on the basis of pixel signals output from a plurality of pixels that are arranged in a planar manner. Also, the pixel signals output from the pixels are, for example, converted from analog into digital form and output by a plurality of AD (Analog to Digital) converters that are arranged for each column of pixels in parallel.
In such an imaging element, an imaging element has been proposed that handles an AD conversion process faster by performing a counting process in down-count and up-count modes (refer, for example, to PTL 1).
Also, an imaging element has been proposed that can reduce noise by performing AD conversion of pixel signals at reset level and pixel signals at signal level (refer, for example, to PTL 2).